SURF1 and Leigh syndrome: An exception is one case with COX-deficient Leigh syndrome reported in 1977.49 Thirty years later, a homozygous c.370C>A SURF1 gene mutation was identified in this patient.50 The dominant ultrastructural feature of this case was enlarged mitochondria of bizarre shape and various size and form, aggregated in juxtanuclear and subsarcolemmal regions.